This plan is directed to produce a panel of human monoclonal antibodies (McAb) against human osteosarcoma associated antigens (OSAA) from cloned human lymphoblastoid cells. Human lymphoblastoid cells will be established by infecting B lymphocytes with Epstein-Barr virus (EBV) from the B lymphocytes obtained from peripheral blood or from lymph nodes of osteosarcoma patients and the household contacts who have high titers of antibody against OSAA. OSAA specific antibody producing lymphoblastoid cells will be fused with human myeloma cells, human lymphoblastoid cells and murine myeloma to produce stable hybrids for antibody production. The specificity of the McAbs will be investigated by using human osteosarcoma target cells, tumor cells of various histologic types, normal tissues and normal human bone marrow. The cytotoxic effects of the McAb will be studied by complement dependent cytotoxocity assay and cell dependent cytotoxicity (ADCC) assay. The OSAA reaction with the panel of McAb will be characterized (molecular weight, antigenicity, enzyme sensitivity, lectin-binding, SDS-PAGE, IEF, immunoprecipitation, and Western blot technique). Anti-idiotypic antibodies will be produced in rabbits using anti-OSAA McAb. Human IgM produced by SKW 6.4 cells will be used as control for the preparation of anti-idiotypic antibody. The idiotypes of the McAbs and the anti-OSAA antibody from patients with osteosarcoma and their household contacts will be investigated. The human McAb(s) obtained from this project will be valuable in the development of McAb therapy of osteosarcoma either by using the McAb alone or conjugates of McAb with cytotoxic drugs.